This is a case-control epidemiological study of prolapsed lumbar inter-vertebral disc and prolapsed cervical intervertebral disc. Demographic characteristics and exposure to possible risk factors in surgical, probable, and possible cases of each of these conditions in the age range 20-64 years will be compared to demographic characteristics and exposure to possible risk factors in two control groups in the same age range. One control group will be composed of people without known spinal disorders and the second will comprise people with back and neck problems other than prolapsed discs. Information on demographic variables and exposure to possible risk factors is obtained by means of a structured questionnaire administered by trained interviewers. The questionnaire covers symptoms of current and previous back, neck, leg, and arm problems; respiratory symptoms; exdemographic variables; pregnancy history; occupational history; driving motor vehicles on the job; driving other than on the job; use of other modes of transportation; participation in certain sports; handedness; height; weight; and disability and limitation of activity. The data collection is expected to be complete in the Fall of 1981.